<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <title>BFC</title>
        <style>
            *{
                margin: 0;
                padding: 0;
            }
            ul{
                border: 5px solid rgb(91, 243, 30);
                width: 500px;
                list-style: none;
                overflow: hidden;
            }
            li{
                border: 5px solid rgb(233, 250, 84);
                width:200px;
                height:200px;
                float: left;
            }
        </style>
    </head>
    <body>
        <!--计算BFC的高度时，浮动元素也参与计算。-->
        <ul>
            <li>s1</li>
            <li>s2</li>
        </ul>
    </body>
</html>